Optical combiner apparatus

ABSTRACT

Optical combiners are provided. The optical combiner may have a see through optically transparent substrate and a patterned region included in the optically transparent substrate and disposed along a wave propagation axis of the substrate. The patterned region may be partially optically reflective and partially optically transparent. The patterned region may comprise a plurality of optically transparent regions of the optically transparent substrate and a plurality of optically reflective regions inclined relative to the optical transparent substrate wave propagation axis. Augmented reality optical apparatus, such a head up display, may include the optical combiner.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 16/845,018, filed Apr. 9, 2020, entitled “OpticalCombiner Apparatus” in the name of DAQRI LLC, which is a divisional ofU.S. Non-Provisional patent application Ser. No. 15/206,111, filed Jul.8, 2016, entitled “Optical Combiner Apparatus” in the name of DAQRI LLC,the entire disclosures of which are incorporated herein by reference asif fully set forth herein.

TECHNICAL FIELD

Embodiments relate to optical combiner apparatus and components thereof.More particularly but not exclusively, embodiments relate to augmentedreality image combiners. Additionally, some embodiments relate to headmounted displays including optical combiners.

BACKGROUND

An optical see through combiner is a fundamental component in anaugmented reality display system. The optical combiner enables the realworld and an artificially generated scene created by a computer andcreated by a projector to be optically superimposed.

There are a number of optical systems that have been proposed andadopted with one of the main requirements is to take the projectionsystem away from the eye so it does not obscure the natural view of theworld. However, high performance optical combiner systems are complexand difficult to fabricate.

There is a need to provide improved optical combiners that are easier tomanufacture and have better performance than current optical systems.

SUMMARY

According to a first aspect, there is provided an optical combiner. Theoptical combiner may comprise an optically transparent substrate and apatterned region included in the optically transparent substrate anddisposed along a wave propagation axis of the substrate. The patternedregion may be partially optically reflective and partially opticallytransparent. The patterned region may comprise a plurality of opticallytransparent regions of the optically transparent substrate and aplurality of optically reflective regions inclined relative to theoptical transparent substrate wave propagation axis.

By including in the optical substrate a patterned region which ispartially optically reflective and partially optically transparent,improved optical combiners are provided that are easier to manufactureand have better performance.

According to another aspect, an augmented reality optical combiner isprovided. The optical combiner may comprise a transparent opticalwaveguide substrate for receiving an optical image and viewing therethrough a distant real world scene and a plurality of reflectiveelements arranged within the transparent optical waveguide forreflecting the received optical image. The plurality of reflectiveelements may be arranged in such a way that, when the optical combineris in use, the received optical image is reflected and superimposed onthe real world scene view so as to allow viewing of the distant realworld scene while simultaneously viewing the optical image superimposedon the real world scene.

According to yet another aspect, an augmented reality optical apparatusis provided. The augmented reality optical apparatus may comprise a headmounted display and at least one of the aforementioned optical combinerssupported on the head mounted display.

According to yet other aspects, methods of combining optical rays areprovided. In one aspect, a method of combining optical rays comprisespropagating first optical image rays along a length of an opticaltransparent waveguide substrate towards a pattern region included insaid optical transparent substrate; transmitting second optical imagerays through a width of the optical waveguide substrate; and selectivelyreflecting out of said optical substrate said first optical image raysat different points along said substrate from reflective regions of saidpattern region; said reflected first optical image rays superimposing onsaid second optical image rays transmitted out of said opticaltransparent substrate.

The first optical image rays may be computer generated rays. The secondoptical image rays may be from a distant real world scene. The patternregion may be a pattern region as set forth hereinbefore.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention may be more readily understood,reference will now be made to the accompanying drawings, in which:

FIG. 1 is a front perspective view of an exemplary optical combiner inaccordance with an embodiment;

FIG. 2A is a top plan view of an optical combiner in accordance with anembodiment for use with an image projector;

FIG. 2B is a front view of the optical combiner of FIG. 2A;

FIG. 3A is a front view of a sparse aperture reflector in accordancewith an embodiment;

FIG. 3B is a side view of the sparse aperture reflector of FIG. 3A;

FIG. 4A is a front view of a sparse aperture reflector in accordancewith another embodiment;

FIG. 4B is a side view of the sparse aperture reflector of FIG. 4A;

FIG. 5 is a schematic diagram showing generally how an augmented realityimage combiner combines images according to one embodiment;

FIG. 6 is a schematic diagram showing in detail how an augmented realityimage combiner combines images according to an embodiment;

FIG. 7 is a front view of augmented reality head mounted display glassesaccording to an embodiment;

FIG. 8 is a front view of an augmented reality head mounted displayhelmet according to an embodiment;

FIG. 9 is a front perspective view of an exemplary optical combiner inaccordance with another embodiment; and

FIG. 10 is a partial view showing reflective elements of the opticalcombiner tilted at different angles relative to the common plane inwhich they are disposed according to one embodiment

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particularembodiments, procedures, techniques, etc. in order to provide a thoroughunderstanding of the present invention. However, it will be apparent toone skilled in the art that the present invention may be practiced inother embodiments that depart from these specific details.

Referring now to the accompanying drawings, FIG. 1 shows a front view ofan exemplary optical combiner in accordance with an embodiment. Opticalcombiner 100 is formed from an optically transparent waveguide substrate105. Substrate 105 has a wave propagation axis 106 extending along alength of the waveguide substrate. Optical image rays entering anoptical receiving end or side of substrate 105 propagate through thesubstrate along the propagation axis 106.

Substrate 105 is a see-through substrate made from optical waveguidesubstrate material such as but not limited to glass or plastic. Opticalrays 150 entering the substrate rear face pass through the substratematerial and exit from the substrate front face. An observer located onone side of the substrate and looking through the front face of thesubstrate can see through the substrate material and observe objects,scenes etc. located on the other side of the substrate.

A patterned region 107 is included in a volume of the opticallytransparent substrate. Patterned region 107 is partially opticallyreflective and partially optically transparent. Patterned region 107comprises a plurality of optically transparent regions 109 of opticallytransparent substrate 105 and a plurality of optically reflectiveregions 108 inclined relative to optical transparent substrate wavepropagation axis 106. For sake of clarity, not all reflective regionsare shown and not all shown reflective regions 108 and transparentregions 109 have been labeled with reference numerals. Optical imagerays 140, which are captured in an end of the substrate, propagate alongpropagation axis 106, pass into patterned region 107, and areselectively reflected at different points along substrate 105 byinclined optical reflective regions 108. The reflected optical imagerays 142 exit the front face of substrate 105.

For ease of illustration, rays 140 are shown only as straight throughrays. There are countless other rays that bounce along the waveguiderather than passing straight through which are not shown (examples aregiven in FIGS. 2A, 2B & 6 of a bouncing ray). In some embodiments,patterned region 107 is a regular patterned region. In some otherembodiments, pattern region 107 is an irregular patterned region or acombination of a regular pattern region and an irregular patternedregion.

The patterned region can take various forms. In some embodiments,optically reflective regions 108 of pattern region 107 are a pluralityof optically reflective elements distributed in optically transparentsubstrate 105, for example as shown in FIG. 1 , and opticallytransparent regions 109 are regions of optical transparent substratematerial 105 unoccupied by the plurality of reflective elements. In someother embodiments, pattern region 107 is a reverse design in which andoptically transparent regions comprise a plurality of apertures oropenings formed in reflective material layer or volume included in thesubstrate and optically reflective regions comprise the opticallyreflective material.

In the optical combiner of FIG. 1 , optical reflective regions 108comprise optical reflective elements which are reflective dots. For easeof explanation and visualization, in FIG. 1 and the other accompanyingfigures, reflective dots are shown enlarged and not to scale.Furthermore, not all reflective dots are shown. In practice, there arefor example typically thousands of small reflective dots in thesubstrate and the dots are small enough that they cannot easily be seenby the human eye so that they do not substantially disrupt the seethrough performance of the optical combiner. In some embodiments, theoptical reflective elements may be other types of discrete reflectiveelements such as reflective symbols, characters or the like rather thanreflective dots.

In some embodiments, each of at least some of the reflective dots orother elements are fully reflective. In some other embodiments, each ofat least some of the reflective dots or other reflective elements ispartially reflective. For example, at least some of the reflective dotseach have reflectivities between 5-100%. In some embodiments, thereflectivites of at least some of the reflective elements are the same.In some embodiments, the reflectivities of at least some of thereflective elements are different.

Optical reflective dots are each made of a reflective material such asbut not limited to a single reflective metal layer or multiple layers ofreflective oxides or other materials. The reflective dot material maydeposited by known deposition techniques. In some embodiments, injectionforming with over-molded reflective layers and optical 3D printing, maybe used to form the optical substrate including the pattern region. Inthe embodiment of FIG. 1 , reflective dots are distributed in aplurality of distinct planes 115, 120, 125, 130 spaced apart along alength of substrate. Each plane 115, 120, 125, 130, extends between topand bottom sides of substrate 105 and is inclined relative topropagation axis 106 as shown in FIG. 1 . Reflective dots in each planehave a regular pattern and shape such as the rectangular matrix ofsquare dots illustrated in FIG. 1 . However, in other embodiments, thepattern of reflective dots in one or more of the planes can have otherregular shaped matrixes or patterns, or can have an irregular pattern.Furthermore, as will be explained in more detail below, the shape, size,tilt, and/or spacing of each reflective dot, or at least some reflectivedots, can be the same or can be different from one another.

Additionally, in some embodiments, reflective dots 108 are distributedin a volume section of the substrate that extends beyond each distinctplane 115, 120, 125, 130. By way of example, FIG. 1 illustratesreflective dots 108 are distributed in the distinct planes 115, 120,125, 130 and also occupy intermediate regions of the substrate betweenthe planes. In some embodiments of the optical combiner, reflective dots108 are not distributed in distinct planes but rather are distributedthroughout distinct volume sections spaced apart along a length of thewaveguide substrate.

In any event, irrespective of how reflective elements are exactlydistributed in the different embodiments, the reflective elements canform groups that are spaced along a length of substrate 105. Forexample, in FIG. 1 , a first group 101 of reflective dots is arrangedfor partially reflecting optical image rays propagating along a lengthof substrate 105. Reflective elements of subsequent groups 102, 103, 104spaced apart further along the wave guide are arranged for reflectingoptical image rays unreflected by the first group of reflectiveelements.

Each group of reflective dots distributed about a distinct plane and/ora distinct volume section together with optical transparent substrategaps therebetween collectively operate as a partially reflectiveindividual reflector. FIG. 1 illustrates four such individualreflectors. However, in other embodiments, the optical combiner may haveany number of such reflectors ranging from a single reflector to manyreflectors.

Optical combiner 100 is an extremely simple structure made up ofreflective elements rather than reflectors which have a complex set ofreflective layers coated over the entire area of each reflector.

Operation of the optical combiner as an optical image combiner is verysimple, when the rays that form the image travel along the waveguidesubstrate some of them hit reflective dots of the first reflector andare re-directed towards the eye. The majority of the rays miss the dotsas they only occupy a small area of the first reflector. If for examplethe dots occupy 5% of the overall area then overall reflectivity isabout 5% too and 95% of the image energy passes through to the nextreflector and so on. The reflective dots reflect optical rays 140 thathave propagated straight through into the substrate but also the otherrays 140 that arrive via a wide “bounce” and hit the reflective dots ata glancing angle (see for example the optical combiners shown in FIGS.2A, 2B & 6 for examples of bouncing oncoming rays and reflections fromreflective dots).

In some embodiments, the first reflector (group of dots 101) has arelatively low reflectivity (small area of dots) and subsequent oneshave greater reflectivity (bigger area of dots) increasing reflectivitythe further along the waveguide substrate. The dot area to opticaltransparent gap ratio is varied to obtain chosen reflectivity for eachreflector.

In yet some other embodiments, all reflective dots 108 are distributedthroughout a substrate volume extending along a length of the waveguiderather than occupy distinct planes and/or distinct volume sections. Insuch embodiments, reflective dots 108 and optically transparent gaps orregions therebetween effectively form one continuous partiallyreflective reflector extending through the substrate volume. FIG. 9illustrates one such optical combiner 900 according to an embodiment.Reflective dots 108 are shown distributed throughout a volume ofsubstrate 105. As already mentioned, for ease of illustration not allreflective dots are shown. Furthermore, the specific pattern of dotsshown in FIG. 9 is merely an example dot pattern. The reflective dots108 are still arranged so that the relatively reflectively increasesfrom low to high further along the continuous reflector.

In yet some other embodiments of the optical combiner, the opticalsubstrate is a non see-through substrate.

FIGS. 2A & 2B show the top & front views, respectively, of an opticalcombiner for use with an optical image generator according to anembodiment. Optical combiner 200 is a slab 205 (flat, parallel sides) ofglass or plastic, or other optically transparent waveguide for near eyedisplays. In alternative embodiments, the waveguide is curved and thefaces may not necessarily be parallel. Optical combiner 200 is similarto optical combiner 100 but for ease of fabrication each partiallyreflective reflector is a sparse aperture reflective surface made up ofa surface pattern of the reflective dots or other types of reflectiveelements. There is an array of four such reflectors 215, 220, 225, 230shown in FIGS. 2A & 2B but optical combiner 200 can have any number andtypically 3 and 6. Reflector 215 has the lowest reflectivity in thearray, reflector 220 has the next highest reflectivity, reflector 225the next highest reflectivity and reflector 240 the highestreflectivity. By way of example, in some embodiments, first reflector215 has a reflectivity of about 5-7%, second reflector 220 has areflectivity of about 10%, third reflector 225 has a reflectivity of 20%and fourth reflector 230 with a reflectivity of about 80%.

Sparse aperture surface reflectors 215-230 comprise a plurality ofreflective dots (such as dots 108), or other reflective elements, thatare formed on a surface and can have many different configurations. Insome embodiments, the reflective dots or other elements are arbitraryshapes and are arranged in a matrix on the surface in randomizedpositions. Reflective dots may be positioned about the surface in adeterministic manner or according to a random function.

In FIGS. 2A & 2B the optical source for generating optical image rays140 is an image projector 265. A simplified situation is depicted inFIGS. 2A & 2B showing how a single ray 275 originating from theprojector 265 is optically coupled into the waveguide substrate 205using a prism 270. However, other optical coupling methods are possibleincluding direct injection into the end of the waveguide, such as shownin FIG. 1 as rays 140. In other embodiments, other optical generatorsmay be used instead of, or in addition to, projector 265.

One such sparse aperture reflector surface is shown in more detail inFIGS. 3A & 3B, which illustrate a plan view and side view, respectively,of a sparse aperture reflector system according to one embodiment (foruse as one or more of the reflectors 215-230 in the optical combiner ofFIGS. 2A & 2B). For ease of fabrication, sparse aperture reflectorsystem 330 has a simple matrix 350 of reflective dots 180 or otherelements on a regular XY pitch 305. In FIGS. 3A & 3B, reflective matrix350 is carried on a separate optically transparent substrate which whenassembled with the other reflectors forms part of the optical waveguidesubstrate 205. In some other embodiments, reflective matrix 350 isformed directly on a surface of an intermediate region of the waveguidesubstrate 205 (see for example intermediate regions of 245-260 of FIGS.2A & 2B). The height A of sparse aperture reflector surface 330 istypically but not limited to 35-50 mm but will vary depending on thespecific optical combiner characteristics desired. The width B of sparseaperture reflector surface is determined according to the number ofreflectors required in the optical combiner and according to thethickness of the optical wave guide substrate. The thickness T1 of thereflective dots or other elements will vary but is typically but notlimited to 0.1-1 micrometers (μm).

FIGS. 4A & 4B illustrate a plan view and side view, respectively, of asparse aperture reflector system according to another embodiment (foruse as one or more of the reflectors 215-230 in the optical combiner ofFIGS. 2A & 2B). Sparse aperture reflector system 400 differs from thesystem 300 in the arrangement and parameters of the reflective dots orother elements. As shown in FIGS. 4A &4B, the reflective dots patternedon the front face of the reflector system have some different shapes.The dot shapes are regular shapes and/or random shapes. By way ofexample, in FIGS. 4A & 4B, first dot 420 has an arbitrary shape andsecond dot 415 has an arbitrary shape. Reflective dots have differentseparation distances. The reflecting dot thickness may also vary fordifferent reflective dots. Optical combiner performance and imaging canbe controlled and improved by optimization of various reflectorparameters including but not limited to the following: shape of the dots(regular or random shapes), minimum dimension of a dot feature, maximumdimension of a dot feature, degree of randomization over surface,thickness of dot reflecting material, minimum separation between dots,maximum separation between dots and fraction of area occupied by dots.In some embodiments, at least some reflective dots or other elementshave a fully or substantially reflective front side and fully orsubstantially absorbing rear side. As shown in FIGS. 4A & 4B, somereflective dots or elements include a buried relief reflector 460 and apositive relief reflector 455.

In some embodiments of the optical combiners described herein, at leastsome of the reflective elements 108, etc. in the optical substrate aretilted at different angles from one another and/or at least some of thereflective elements are tilted in parallel with one another. Also, insome further embodiments, some of the reflective elements areindividually tilted relative to the planes occupied by the reflectiveelements. By way of example FIG. 10 , is a partial view of the opticalcombiner showing reflective elements (in this case rectangularreflective dots) 1002, 1008 tilted at different angles relative tocommon plane 1000 in which they are occupied in the optical substrateaccording to one embodiment. First reflective dot 1002 is tilted in thex axis by a first angle 1004 relative to common plane 1000 whereassecond reflective dot 1008 is tilted in the x axis by a second angle1010 relative to the common plane, the second angle 1010 being differentfrom the first angle 1004. Also, first reflective dot 1002 is tilted inthe Z axis by a third angle 1006 relative to common plane 1000 whereassecond reflective dot 1008 is titled in the z axis by a fourth angle1012 relative common plane 1000, the fourth angle 1012 being differentfrom the third angle 1006. In other embodiments, at least some of thereflective elements can be tilted in x, y, z planes (or any combinationthereof) differently or in the same way)

The optical combiners of the described embodiments have many advantagesover known waveguide reflectors. The optical combiners of embodimentsare insensitive to input polarization unlike known combiners thatrequire careful polarization control on transit through the reflectors.The optical combiners of embodiments have inherently broadband opticalbandwidth unlike known combiners that require careful design to makesure reflectivity is maintained over a wide range of incidence angles.The optical combiners of embodiments are less complex because patternsof reflective dots or other elements can be fabricated using a singlelayer of reflective material. In contrast, in known combiners eachreflector array will require 20 to 30 separate carefully depositedlayers to make one reflecting surface. The optical combiners are easilyfabricated and robust compared to known combiners which are difficult tomanufacture due to the highly complex multiple layers of reflectivefilms and the fragile nature of the multilayers.

In some aspects, the optical combiners can be used for combiningaugmented reality images and a real world scenes. As indicated by FIG. 5, an augmented reality image combiner 515 is an optical structure thatoverlays the real world scene 505 with an optically projected computergenerated image 510 and relays the combined image into the eye or eyes500 of an observer. Optical combiner 515 is any one of the opticalcombiners described hereinbefore with reference to FIGS. 1-4 . Theplurality of reflective dots are arranged in such a way that, when theoptical combiner is in use, the received computer generated opticalimage is reflected and superimposed on the real world scene view.

In order to more adequately illustrate how the images are combined in anaugmented reality image combiner, reference is made to FIG. 6 which is asimplified schematic of an augmented reality optical combiner systemaccording to an embodiment. This figure demonstrates how an opticallyprojected computer graphic rays contained within the waveguide arerelayed into the observer's eye and how rays from the real world scenepass through. Optical combiner 600 can be any one of the opticalcombiners described hereinbefore with reference to FIGS. 1-4 . However,for ease of explanation FIG. 6 has been greatly simplified to show threespaced apart sparse reflectors and show only four reflective dots oneach sparse reflector. By way of example, guided rays 620, 625, 630originating from a projected image 615 are captured in an opticalreceiving end of the optical waveguide substrate and are relayed towardsthe observer's eye 605. In particular, example guided ray 620originating from the projected image 615 captured in the waveguide isrelayed towards the observer's eye 605 off a reflective element formedon sparse area reflector n=1 635. Furthermore, example guided ray 625originating from the projected image 615 and captured in the waveguidepasses through transparent region of sparse area reflector 635 andsubsequent transparent region of sparse area reflector n=2 640. Yetfurthermore, example guided ray 630 originating from the projected image615 captured in the waveguide is relayed towards the observer's eye 605off a reflective element formed on sparse area reflector n=2. Arbituraybundle of rays 650 originating from the real scene pass through theoptical combiner.

In some aspects, one or more of the optical combiners are incorporatedin head mounted displays. In some embodiments, a pair of the opticalcombiners are included in glasses or Goggle form factor augmentedreality head mounted displays. FIG. 7 shows a front view of a pair ofthe head mounted display glasses according to one embodiment. Glasses orGoggle type head mounted display 700 has a processing module 705generating computer formed images for binocular view. A left eye opticalcombiner and projection system 710 and a right eye optical combiner andprojection system 715 are included in the head mounted display. Theoptical combiner in each system 710, 715 is any one of the opticalcombiners of the embodiments described herein with or without referenceto FIGS. 1-6 . Optical image projector 265 and optical coupling 270 forexample may form part of the projector system. An opto-mechanical frame720 holds the optical parts securely and in the correct geometricalignment.

In some embodiments, the formed images are for monocular view and onlyone of the optical combiner and projection systems 710, 715 is includedin the head mounted display.

In some embodiments, the head mounted display in which one or more ofthe optical combiners is incorporated is a helmet form factor augmentedreality head mounted display. FIG. 8 shows a front view of a headmounted display helmet according to one embodiment. Helmet head mounteddisplay 800 has a processing module 805 generating computer formedimages for binocular view. A left eye optical combiner and projectionsystem 815 and a right eye optical combiner and projection system 820are included in the head mounted display. The optical combiner in eachsystem 815, 820 is any one of the optical combiners of the embodimentsdescribed herein with or without reference to FIGS. 1-6 . Optical imageprojector 265 and optical coupling 270 may for example form part of theprojector system. An opto-mechanical sub frame 810 holds the opticalparts securely and in the correct geometric alignment. Opto-mechanicalsub frame 810 is supported by a mechanically robust shell 835 of thehelmet.

In some embodiments, the formed images are for monocular view and onlyone of the optical combiner and projection systems 815, 820 is includedin the head mounted display.

It will be appreciated that various of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications such as headup type displays.

Various presently unforeseen or unanticipated alternatives,modifications, variations, or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims. For example, the head mounteddisplay sets may be visors, goggles or headband structures and are notlimited to the particular types shown in the Figures. Likewise the shapeof the optical combiner substrates may be any shape that is capable ofguiding and combining images in the manner described hereinbefore.

The description of the present disclosure has been presented forpurposes of illustration and description, but is not intended to beexhaustive or limited to the present disclosure in the form disclosed.Many modifications and variations will be apparent to those of ordinaryskill in the art without departing from the scope and spirit of thepresent disclosure. Exemplary embodiments were chosen and described inorder to best explain the principles of the present disclosure and itspractical application, and to enable others of ordinary skill in the artto understand the present disclosure for various embodiments withvarious modifications as are suited to the particular use contemplated.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. The descriptions are not intended to limit the scope of thetechnology to the particular forms set forth herein. Thus, the breadthand scope of a preferred embodiment should not be limited by any of theabove-described exemplary embodiments. It should be understood that theabove description is illustrative and not restrictive. To the contrary,the present descriptions are intended to cover such alternatives,modifications, and equivalents as may be included within the spirit andscope of the technology as defined by the appended claims and otherwiseappreciated by one of ordinary skill in the art. The scope of thetechnology should, therefore, be determined not with reference to theabove description, but instead should be determined with reference tothe appended claims along with their full scope of equivalents.

The invention claimed is:
 1. An optical combiner comprising an opticallytransparent substrate comprising a volume of optically transparentmaterial defined by a front face, a rear face opposite the front face, afirst end, a second end opposite the first end, and a wave propagationaxis extending along a length of the volume from the first end to thesecond end; optically reflective dots disposed within the volume in afirst direction parallel to the wave propagation axis and a seconddirection perpendicular to the wave propagation axis that reflectoptical image rays emitted from the first end or the second end throughthe front face, wherein the optically reflective dots are inclinedrelative to the wave propagation axis and spaced apart from one anotherin the first direction and the second direction; and transparent regionsdisposed between the optically reflective dots extending in the firstdirection and the second direction.
 2. The optical combiner of claim 1,wherein the optically reflective dots and the transparent regionsdisposed between the optically reflective dots are included in apatterned region of the optically transparent substrate, and wherein thepatterned region comprises an irregular patterned region.
 3. The opticalcombiner of claim 1, wherein the optically reflective dots and thetransparent regions disposed between the optically reflective dots areincluded in a patterned region of the optically transparent substrate,and wherein the patterned region comprises a regular patterned region.4. The optical combiner of claim 1, wherein the transparent regionscomprise regions of the optically transparent substrate unoccupied bythe optically reflective dots.
 5. The optical combiner of claim 1,wherein the optically reflective dots are distributed in a plurality ofplanes spaced apart along the wave propagation axis.
 6. The opticalcombiner of claim 5, wherein the optically reflective dots are alsodistributed in intermediate regions of the optically transparentsubstrate between respective planes of the plurality of planes.
 7. Theoptical combiner of claim 5, wherein the transparent regions comprisefirst transparent regions disposed between the optically reflective dotswithin the plurality of planes and wherein the optically transparentsubstrate further comprises second transparent regions betweenrespective planes of the plurality of planes.
 8. The optical combiner ofclaim 1, wherein the optically reflective dots are arranged in at leastone regular array.
 9. The optical combiner of claim 1, wherein theoptically reflective dots are fully reflective elements.
 10. The opticalcombiner of claim 1, wherein the optically reflective dots respectivelycomprise a fully or substantially reflective front side and fully orsubstantially absorbing rear side.
 11. The optical combiner of claim 1,wherein at least some of the optically reflective dots comprise tilteddots which are tilted parallel to each other.
 12. The optical combinerof claim 11, wherein the tilted dots are distributed within a sameplane.
 13. The optical combiner of claim 11, wherein the tilted dots aredistributed within different planes.
 14. The optical combiner of claim11, wherein the tilted dots are distributed throughout the volume of theoptically transparent substrate.
 15. The optical combiner of claim 1,wherein the optically dots comprise groups of dots, the groups of dotsbeing spaced apart along the optically transparent substrate, wherein afirst group of the groups of dots is arranged for partially reflectingfirst optical image rays propagating along the wave propagation axis,and wherein at least one second group of the groups of dots is arrangedfor reflecting second optical image rays that are not reflected by thefirst group.
 16. The optical combiner of claim 1, wherein a size, shape,and spacing of the optically dots varies.
 17. The optical combiner ofclaim 1, wherein a size, shape, reflectivity, number and/or distributionof the optically dots is electronically adjustable to adjust areflectivity to transmission ratio of the optical combiner.
 18. Anoptical combiner comprising an optically transparent substratecomprising a volume of optically transparent material defined by a frontface, a rear face opposite the front face, a first end, a second endopposite the first end, and a wave propagation axis extending along alength of the volume from the first end to the second end; and apatterned region included within the volume of the optically transparentsubstrate; wherein the patterned region comprises optically transparentregions and optically reflective regions; and wherein the opticallyreflective regions comprise reflective dots that are distributedthroughout a portion of the volume in a first direction parallel to thewave propagation axis and a second direction perpendicular to the wavepropagation axis, wherein the reflective dots are inclined at an anglerelative to the wave propagation axis and spaced apart from one anotherin the first direction and the second direction, and wherein thereflective dots reflect rays emitted from the first end or the secondend through the front face.
 19. The optical combiner of claim 18,wherein the patterned region comprises an irregular patterned region.20. The optical combiner of claim 18, wherein the patterned regioncomprises a regular patterned region.
 21. The optical combiner of claim18, wherein the optically transparent regions comprise regions of theoptically transparent substrate unoccupied by the reflective dots. 22.The optical combiner of claim 18, wherein the reflective dots aredistributed in a plurality of planes of the optically transparentsubstrate and spaced apart along the wave propagation axis.
 23. Theoptical combiner of claim 22, wherein the reflective dots are furtherdistributed in intermediate regions of the optically transparentsubstrate between respective planes of the plurality of planes.
 24. Theoptical combiner of claim 22, wherein the reflective dots are inclinedat a same angle relative to the wave propagation axis.
 25. The opticalcombiner of claim 18, wherein the reflective dots are arranged in atleast one regular array.
 26. The optical combiner of claim 18, whereinthe reflective dots comprise fully reflective elements.
 27. The opticalcombiner of claim 18, wherein the reflective dots respectively comprisea fully or substantially reflective front side and fully orsubstantially absorbing rear side.
 28. The optical combiner of claim 18,wherein the reflective dots comprise two or more tilted reflective dotsthat are tilted parallel to each other.
 29. The optical combiner ofclaim 28, wherein the two or more tilted reflective dots that aredistributed within a same plane.
 30. The optical combiner of claim 28,wherein the two or more tilted reflective dots that are distributedwithin different planes.
 31. The optical combiner of claim 18, wherein asize, shape, and spacing of the reflective dots varies.
 32. The opticalcombiner of claim 18, wherein a size, shape, reflectivity, number and/ordistribution of the reflective dots is electronically adjustable toadjust a reflectivity to transmission ratio of the optical combiner.